1. Field of the Invention
The present invention relates to a method for appropriately marking a semiconductor wafer in order to enable correct identification of the semiconductor wafer, as well as to a semiconductor wafer marked by said method.
2. Background Art
In the event failures are found to have arisen during the course of manufacture or after shipment of semiconductor wafers, such as silicon wafers, accurate reporting of the failures to a manufacturing facility is very important for determining sources of the failures without fail.
In order to enable such feedback, individual wafers which are under manufacture must be identifiable. To this end, individual semiconductor wafers are marked at initial stages in the process of manufacture.
Marking of semiconductor wafers is usually implemented, by means of making a certain impression on specified locations of individual wafers which are under manufacture. In order to achieve this, a laser marking machine (described in, for example, Japanese Patent Application Laid-Open Nos. 23512/1984 and 175154/1990), for example, is used.
A typical mark to be inscribed on an individual wafer is an ID number. There may be a case where a mark, such as a bar code, a character, or a numeral, is inscribed on the surface of a wafer as information about processing conditions, processing history, or electrical properties. In this case, a mark can be used for process and production control, as well as for tracing the source and route of failures. Consequently, wafers can be identified during the course of manufacture or after shipment.
A marking operation involves application of any physical action to a wafer which is under manufacture. For this reason, there may arise a case where slips arise in a wafer for reasons of marking operation. In order to prevent an adverse effect on a wafer, which would otherwise be imposed by a marking operation, marking a wafer on the smallest possible scale is preferable.
Inscription of a minute mark is preferable in terms of protection of a wafer from an adverse effect. However, a minute mark is easily effaced by surface treatment to which a semiconductor wafer is to be subjected during the course of manufacturing process. Needless to say, manufacture of semiconductor wafers is incessantly performed on a production line. If a semiconductor wafer whose mark is effaced is mingled with other semiconductor wafers, finding the semiconductor wafer and restoring the thus-found wafer to its original condition is very difficult.
The present invention has been conceived in light of the foregoing problems and is aimed at providing a method of inscribing marks on a semiconductor wafer, which marks are less susceptible to surface treatment performed during the course of manufacture, as well as a semiconductor wafer for distribution.